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question regarding electrolysis

06-21-2010, 06:37 PM

i'm working on a commercial job that calls for .040 clear anodized aluminum flashing (yeah i know) around a bunch of wall openings, and even to separate hardi-board siding on beveled 1x2 slats and the 2-inch on center vertical cedar 2x2s on 1x2 slats. the wall's literally sealed with some stupid vapor barrier. as a roofer, i know that any leaks will be blamed on us.

so about the steel pancake screws they gave me to put all the flashing on the wall, and the galvanized light trough that rests against a piece of aluminum. wouldn't that cause everything to corrode? maybe the anodization would help with the light trough situation, but wouldn't the screws rust and even cause the aluminum to corrode? i'm looking for a time-line here if anyone has experience with aluminum-on-steel corrosion. thank ya'!

Yep! You got it right! Alu & Steel in contact, in a wet environment corrodes so you wouldn't believe it! However, if you use plastic or rubber washers under the screws, and avoid electrical contact, then things are going to do OK